Biosensors

https://www.crowdsupply.com/upside-down-labs/bioamp-exg-pill#products

Grove GSR Sensor.   $10.90
https://www.seeedstudio.com/Grove-GSR-sensor-p-1614.html

Heart Rate/Pulse Sensor.     $4.00
https://www.amazon.com/Comimark-Sensor-Module-Arduino-Raspberry/dp/B07V6VV8CM/ref=sr_1_5?crid=2H5T1W8IGAV5T&dib=eyJ2IjoiMSJ9.K09VXKOqKWMlus1pCOomZnJAOrjumlxedmfuFX17fTbvoIHPQu-7ATx5w2VUy8nDg537PJDpxFror3mF58p5Cw-B_BAUFi3-ijN1uknbSOaGJ5xlLh8OtjK5oix5Gg4_Zz7VYQPeYpvTmsdknCPLlNUX14ePwzMhHknVWtC9VAr4RISM3oqaBC03DssfFkxSgCb-u_m_LI7l2tD5F1FSR_nUXMnLYEaf9Pm5Wd3fo2qel60yJlYI6ohoNaIqeWV7TFmhl6QcWyaVEyax1pt1pGfYYyPFaPVLxcWSYGZ6Tw0.Ag9nJqgtrT_FHF8EUJNUubBs72FOW9ZhtUqsctdJOk4&dib_tag=se&keywords=Arduino+Skin+temperature+sensor&qid=1725591308&s=electronics&sprefix=arduino+skin+temperature+sensor%2Celectronics%2C118&sr=1-5

Gy-521 MPU-6050 MPU6050 Module 3 Axis Analog Gyro Sensors+ 3 Axis Accelerometer Module
$5.99

https://wiki.seeedstudio.com/Grove-Chest_Strap_Heart_Rate_Sensor/

Other Biomedicine sensors: https://wiki.seeedstudio.com/Sensor_biomedicine/

EMG Sensor $26.00
https://www.seeedstudio.com/Grove-EMG-Detector-p-1737.html